sync: Gracefully handle very early shutdown

sync/engine/sync_scheduler_impl.h

 // Copyright 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef SYNC_ENGINE_SYNC_SCHEDULER_IMPL_H_
 #define SYNC_ENGINE_SYNC_SCHEDULER_IMPL_H_
 
 #include <map>
 #include <string>
 
@@ skipping 36 matching lines @@
                     BackoffDelayProvider* delay_provider,
                     sessions::SyncSessionContext* context,
                     Syncer* syncer);
 
   // Calls Stop().
   virtual ~SyncSchedulerImpl();
 
   virtual void Start(Mode mode) OVERRIDE;
   virtual bool ScheduleConfiguration(
       const ConfigurationParams& params) OVERRIDE;
-  virtual void RequestStop() OVERRIDE;
+  virtual void Stop() OVERRIDE;
   virtual void ScheduleLocalNudge(
       const base::TimeDelta& desired_delay,
       ModelTypeSet types,
       const tracked_objects::Location& nudge_location) OVERRIDE;
   virtual void ScheduleLocalRefreshRequest(
       const base::TimeDelta& desired_delay,
       ModelTypeSet types,
       const tracked_objects::Location& nudge_location) OVERRIDE;
   virtual void ScheduleInvalidationNudge(
       const base::TimeDelta& desired_delay,
@@ skipping 106 matching lines @@
 
   // Helper to restart waiting with |wait_interval_|'s timer.
   void RestartWaiting();
 
   // Determines if we're allowed to contact the server right now.
   bool CanRunJobNow(JobPriority priority);
 
   // Determines if we're allowed to contact the server right now.
   bool CanRunNudgeJobNow(JobPriority priority);
 
-  // 'Impl' here refers to real implementation of public functions.
-  void StopImpl();
-
   // If the scheduler's current state supports it, this will create a job based
   // on the passed in parameters and coalesce it with any other pending jobs,
   // then post a delayed task to run it.  It may also choose to drop the job or
   // save it for later, depending on the scheduler's current state.
   void ScheduleNudgeImpl(
       const base::TimeDelta& delay,
       const tracked_objects::Location& nudge_location);
 
   // Returns true if the client is currently in exponential backoff.
   bool IsBackingOff() const;
@@ skipping 121 matching lines @@
   // The change is to remember that poll timer just fired and retry poll job
   // after credentials are updated.
   bool do_poll_after_credentials_updated_;
 
   DISALLOW_COPY_AND_ASSIGN(SyncSchedulerImpl);
 };
 
 }  // namespace syncer
 
 #endif  // SYNC_ENGINE_SYNC_SCHEDULER_IMPL_H_